Transformers can be used in the distribution of electrical energy by transforming AC voltage from a high level to a low voltage level, or vice versa. Conductor windings that are wound around a toroidal iron core, which has a rectangular cross section, can be used for this purpose.
EP 0 557 549 B1 discloses a method for producing a power transformer which is cast with cast resin and has a cut strip-wound core made from a cold-rolled ferro-alloy which has a preferred direction of magnetization, as well as a toroidal-core transformer produced in accordance with this method.
The distance between the high-voltage winding and the low-voltage winding should be maintained to avoid interference effects. Moreover, the insulation between the two windings can be subjected to as high a loading as possible, if the insulation is constructed with as few defects as possible.
The leakage channel of the windings, which includes a region between the high-voltage winding and the low-voltage winding, can be subjected to forces which result in the formation of cracks in the cast. These forces can result from temperature fluctuations.
Furthermore, forces can result from magnetic flux in the leakage channel between the individual turns of the windings. For example, when the clamping pressure of the windings is insufficient in relation to the occurring forces, permanent winding deformations or winding breakages can occur.